This is such a good question! I mostly ignore them because I have poop bags and pick up after them always, and so I know I am ok really. I have never been questioned.
I say mostly, because really it depends upon where it is. There is a park attached pretty much to a school that we we walk sometimes. The park is ok, it's on leash, and more of a field really. But around where the school actually is, around the bldg is a great place to walk. They have no dog signs. But actually all the means is that we don't want dog poop here. No problem, since I always pick up. I don't really feel they have an issue with me, I don't feel like they are really 'talking' to me.
Yeah, I know there's always one in every crowd that thinks they are 'above' the rules is what non animal people think. But that is not how I look at it. Like I said, I pick up.
But other places, I would have to just see what was around it. If it was a highly patrolled area, patrolled by police, then probably not.
I do walk one place and I wondered if they would ever put up a no dog sign but when I think about it, how could they as there is a vet place right beside it, so they have to have some place to go, and I have seen poop on the ground and wondered if it was them.
Also, since I am so good to pick up, I have used dumpsters that normally I would NEVER put any human trash in, as it's for the business that it's near. But I WILL put dog poop bags because after all, they should be glad I picked up.